High Energy Physics

Finite density systems can be described by effective field theories with non-linearly realized space-time symmetries, whose construction resembles that of the QCD chiral lagrangian. Based on that similarity, one would expect the construction to work equally well classically and quantum mechanically. While that is true for superfluids and solids, one instead finds that for genuine fluids things are made more complicated by the unusual dynamics of their transverse modes, which are not described by a Fock space. Focussing on the incompressible limit for a fluid in 2+1 dimensions, I illustrate its analogy with the ordinary rigid body. Indeed both systems describe motion on a group manifold. Proceeding from this analogy I develop  a consistent quantum mechanical description of a perfect fluid using the known equivalence between the area preserving diffeomorfism group in 2D and SU(N) for N->\infty

Holographic conformal field theories exhibit dramatic changes in the structure of their operator algebras in the limit where the number of local degrees of freedom (N) becomes infinite. An important example of such phenomena is the violation of the additivity property for algebras associated to local subregions. We investigate the consequences of this "additivity anomaly" in the context of holographic duality. We propose that the difference in volumes of bulk dual subregions can be used as a holographic measure for this additivity anomaly of large N boundary algebras. We demonstrate how the additivity anomaly underlies the success of quantum error correcting code models of holography. Finally, we argue that the connected wedge theorems (CWTs) of May, Penington, Sorce, and Yoshida can be re-phrased in terms of the additivity anomaly, allowing for the definition of a generalized scattering region for which a generalization of the CWTs can be formulated such that both the theorem and its converse should hold.

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